An evaluation of the accuracy of CT when determining resectability of pancreatic head adenocarcinoma after neoadjuvant treatment

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Abstract

Background

To evaluate the accuracy of MDCT for determination of resectability R0 after neoadjuvant therapy in patients with pancreatic head adenocarcinoma locally advanced.

Methods

From January 2005 to December 2010, 80 patients with pancreatic head adenocarcinoma underwent multidetector CT before surgery. Of these, 38 patients received neoadjuvant therapy because tumor was considered locally advanced on baseline CT scan. We retrospectively correlated imaging interpretations with operative and histological data and compared results in patients without (control group) or with (neoadjuvant group) preoperative treatment.

Results

41/42 patients in control group and 31/38 patients in neoadjuvant group finally had curative resection. While resection R0 is similar in both groups (83% and 81%), CT accuracy in determining resectability R0 was significantly decreased in neoadjuvant group (58% versus 83%; p = 0.039). CT scan specificity was significantly lower after neoadjuvant therapy (52% versus 88% in control group) due to an overestimation of vascular invasion: 12/31 patients with complete resection in neoadjuvant group were evaluated at high risk of incomplete resection on CT scan. Tumor size tends to be underestimated in control group (−2 mm) and overestimated in neoadjuvant group (+10 mm). T-staging accuracy was decreased in neoadjuvant group (39% versus 78% in control group; p = 0.002).

Conclusion

Neoadjuvant therapy significantly decreases the accuracy of CT scan in determining operability, T-staging, and resectability R0 of pancreatic head carcinoma. Overestimation of tumor size and vascular invasion significantly reduces CT scan specificity after preoperative treatment.

Introduction

Complete surgical resection is currently the only potentially curative treatment for a pancreatic adenocarcinoma [1]; however, only 10–15% of patients benefit from such treatment because their symptoms present late in the disease, and thus, the diagnosis is performed at a locally advanced or metastatic stage in more than 80% of cases [2]. Pancreatic resection is not indicated in cases of advanced disease because this intervention has a high morbidity and mortality, does not improve survival, and may compromise the quality of life of patients who already have a short life expectancy [3].

Although the prognosis of a pancreatic adenocarcinoma remains poor, much progress toward the treatment of this disease has been made in recent years. Improved imaging techniques and a higher spatial resolution have enabled us to better capture the regional and distant spreading of these cancers. Systematic resection of the retroportal pancreatic lamina associated with the possibility of vascular resection has increased the potential for complete surgical resection [4]. Furthermore, the marking of the resection limits by the surgeon in the operating room and the systematic analysis of the posterior edges have enabled us to standardize and optimize histological analysis [5].

Another major advance is the use of preoperative chemoradiotherapy, which may be responsible for a “downstaging” of the tumor in about 30% of patients, allowing us to extend surgical approaches to locally advanced lesions [6]. In these cases, the rates of complete resection and survival are close to those that are found in patients who immediately undergo surgery [7]. Thus, the implementation of neoadjuvant chemoradiotherapy is increasingly recommended as the first-line treatment for locally advanced pancreatic adenocarcinomas, especially those that are classified as “borderline” [8].

The assessment of locoregional extensions in pancreatic cancer is currently largely based on computed tomography (CT) analysis because the negative predictive value of this modality is high (89–100%) [9]; however, local changes that are secondary to chemotherapy and radiotherapy and due to inflammation, fibrosis, or necrosis may be difficult to evaluate or quantify by CT [10]. Very few studies have focused on the semiological patterns of CT scans and the reliability of the scanner in the context of reevaluating the resectability of a tumor after preoperative treatment. The aim of our study was to assess the ability of CT to predict the resectability of pancreatic head adenocarcinomas after neoadjuvant therapy.

Section snippets

Study

Between January 2005 and December 2010, 135 patients underwent surgery in our institution with the intent of curing an adenocarcinoma of the head of pancreas. The preoperative CT scans of 80 of these patients were in our possession, either in our institutional imaging database or in the patient record. Thirty-eight of these 80 patients underwent neoadjuvant treatment because of a tumor that was considered to be “borderline” or locally advanced on the initial CT scan. Thirty-seven of 38 patients

Demographic and clinical data (Table 1)

The average time between CT and surgery was higher in the neoadjuvant group. Preoperative pancreatic biopsies, bile duct bypasses, and clinical infections (cholangitis or cholecystitis) were all significantly more frequent in the neoadjuvant group. The presence of peripancreatic inflammation (visible as a diffuse infiltration into the peripancreatic fat) was more frequently observed after neoadjuvant therapy.

Operability

In the control group, only one patient could not undergo resection because of liver

Discussion

The use of neoadjuvant therapy is commonly accepted as the initial step in the management of patients with “borderline” pancreatic head cancer to increase the likelihood of an R0 resection [8]. However, the CT evaluation of tumor responses after preoperative treatment has not been well explored. In this study, we show that the ability of CT to evaluate operability, T-staging, and histological resectability is reduced after neoadjuvant therapy. The decrease in the diagnostic specificity of the

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